Melanie Beasley, PhD, is the Haslam Postdoctoral Fellow in the Department of Anthropology. Dr. Beasley received her PhD from University of California, San Diego focusing on paleoenvironment reconstruction of a 4 million year old hominin site in East Africa using high resolution stable isotope methods. Prior to that Dr. Beasley received her MA from California State University, Chico where she established the stable isotope prep lab and assisted in forensic anthropology case work. In collaboration with the Forensic Anthropology Center, she is using her postdoctoral fellowship to develop new stable isotope methods for forensic, archaeological, and fossil applications.

Abstract:

The ecological niche exploited by early hominins is assumed to have played an essential role in the origins of our lineage and of bipedalism, a distinguishing characteristic. Paleoenvironmental reconstructions in East Africa often rely on surface-collected fossil fauna even though such collections traditionally combine multiple temporal and geographically dispersed components. This presentation will discuss aridity and rainfall patterns 3.97±0.03 Ma at Allia Bay, Kenya, one of the few sites with material recovered in situ, to refine the definition of the mosaic paleoenvironment of Australopithecus anamensis. Traditional bulk isotopic analysis of tooth enamel distinguishes open from closed (δ13C) and arid from humid (δ18O) habitats of individual animals, but at too large a scale (i.e., aggregates multiple years) to explain the adaptive flexibility of early hominins to ecological variables like seasonality. High-resolution stable oxygen isotopes in fossil faunal tooth enamel (δ18Oen) provide a snapshot of seasonality at Allia Bay suggesting that rainfall amounts were higher and more variable in the past, which would impact the available biomass and other ecological variables during the period Au. anamensis occupied the site. These first-ever site- and time-specific ecological data are a step toward understanding seasonality of an environment at biological timescales to better understand the adaptive flexibility necessary to flourish within mosaic habitats often associated with early hominins.